Avian Influenza and the Threat of an Impending Pandemic
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Transcript of Avian Influenza and the Threat of an Impending Pandemic
Avian Influenza and the Avian Influenza and the Threat of an Impending Threat of an Impending
PandemicPandemic
Eden V. Wells, MD, MPHEden V. Wells, MD, MPHMichigan Department of Michigan Department of
Community HealthCommunity Health
Influenza StrainsInfluenza StrainsType AType A– Infects animals and humansInfects animals and humans– Moderate to severe illnessModerate to severe illness– Potential epidemics/pandemicsPotential epidemics/pandemics
Type BType B– Infects humans onlyInfects humans only– Milder epidemicsMilder epidemics– Larger proportion of children affectedLarger proportion of children affected
Type CType C– No epidemicsNo epidemics– Rare in humansRare in humans
Source: CDC
A’s and B’s, H’s and N’sA’s and B’s, H’s and N’s
Classified by its RNA coreClassified by its RNA core– Type A or Type B influenzaType A or Type B influenza
Further classified by surface proteinFurther classified by surface protein– Neuraminidase (N) – 9 subtypes knownNeuraminidase (N) – 9 subtypes known– Hemagluttin (H) – 16 subtypes knownHemagluttin (H) – 16 subtypes known
Only Influenza A has pandemic Only Influenza A has pandemic potentialpotential
Influenza Virus StructureInfluenza Virus Structure
A/Moscow/21/99 (H3N2)
Neuraminidase
Hemagglutinin
Type of nuclearmaterial
Virustype
Geographicorigin
Strainnumber
Year of isolation
Virus subtype
Differentiating InfluenzaDifferentiating Influenza SeasonalSeasonal
– Caused by influenza A or B strains circulating in humans Caused by influenza A or B strains circulating in humans – ~36,000 human deaths annually in USA~36,000 human deaths annually in USA
Avian– Caused by Influenza A– Shorebirds and water fowl are the reservoir and rarely see
outbreaks, except in current H5N1 strain– Domestic poultry (chickens and turkeys), causes
morbidity and mortality with outbreaks annually worldwide
Pandemic
– When new virus strain occurs
– Humans lack immunity
– Simultaneous epidemics worldwide
– Disease easily transmitted between people
– Significant number of illness and deaths
Influenza A: Influenza A: Antigenic Drift and ShiftAntigenic Drift and Shift
Hemagglutinin (HA) and neuraminadase Hemagglutinin (HA) and neuraminadase (NA) structures can change(NA) structures can change
DriftDrift: minor point mutations: minor point mutations – associated with seasonal changes/epidemicsassociated with seasonal changes/epidemics– subtype remains the samesubtype remains the same
Shift:Shift: major genetic changes major genetic changes (reassortments)(reassortments)– making a new subtype making a new subtype – can cause pandemiccan cause pandemic
Seasonal InfluenzaSeasonal Influenza
October to AprilOctober to April
People should get flu vaccinePeople should get flu vaccine
Children and elderly most proneChildren and elderly most prone
~36,000 deaths annually in U.S.~36,000 deaths annually in U.S.
Avian InfluenzaAvian InfluenzaThe “Bird Flu”The “Bird Flu”
Images from: http://www.usda.gov/oc/photo
Avian InfluenzaAvian Influenza
Infection can be in two formsInfection can be in two forms– ““low pathogenic” (LPAI) - causes mild illness low pathogenic” (LPAI) - causes mild illness
and may go undetectedand may go undetected
– ““highly pathogenic” (HPAI) - affects multiple highly pathogenic” (HPAI) - affects multiple organs, spreads rapidly among birds, organs, spreads rapidly among birds, causes high mortality very quicklycauses high mortality very quickly
Avian Influenza and Avian Influenza and Domestic PoultryDomestic Poultry
Virus is shed in saliva, nasal secretions, and Virus is shed in saliva, nasal secretions, and feces of infected birdsfeces of infected birds
Virus can survive for long periods in feces, Virus can survive for long periods in feces, water, and even on the ground, especially water, and even on the ground, especially when environmental temperatures are lowwhen environmental temperatures are low
Avian influenza is a Avian influenza is a reportablereportable disease in disease in MichiganMichigan
The Role of Animals in The Role of Animals in Influenza A InfectionInfluenza A Infection
Shore Birds and
Wild Waterfowl
Domestic Birds
Mammals
Humans
Countries with H5N1 in PoultryCountries with H5N1 in Poultry(OIE, 8/22/06)(OIE, 8/22/06)
AfghanistanAfghanistanAlbaniaAlbaniaAzerbaijanAzerbaijanBurkina FasoBurkina FasoCameroonCameroonCambodiaCambodiaChinaChinaCote d’ IvoireCote d’ IvoireCyprusCyprusDenmarkDenmarkDijboutiDijboutiEgyptEgyptFranceFranceGermanyGermany
HungaryHungaryIndiaIndiaIndonesiaIndonesiaIraqIraqIsraelIsraelJapanJapanJordanJordanKazakhstanKazakhstanLaosLaosMalaysiaMalaysiaMyanmarMyanmarNigerNigerNigeriaNigeria
•North Korea•Pakistan•Palestian Aut. Territories•Romania•Russia•Serbia and Montenegro•South Korea•Sudan•Sweden•Thailand•Turkey•Ukraine•Vietnam
Domestic Poultry SurveillanceDomestic Poultry Surveillance
• Michigan veterinarians are responsible for overall livestock and poultry reportable disease programs
• They conduct investigations into reports of diseases such as:
– Avian influenza– Rabies– Eastern equine encephalitis– Equine infectious anemia– Tuberculosis– Psittacosis
www.michigan.gov/MDA
Countries with H5N1 in Wild BirdsCountries with H5N1 in Wild Birds(OIE, 8/22/05)(OIE, 8/22/05)
•Afghanistan
•Austria
•Azerbaijan
•Bosnia and Herzegovina
•Bulgaria
•Cambodia
•Cameroon
•China
•Cote d’ Ivoire
•Croatia
•Czech Republic
•Denmark
•Egypt
•France
•Georgia
•Germany
•Greece
•Hungary
•Indonesia
•Iran
•Italy
•Japan
•Kazakhstan
•Kuwait
•Mongolia
•Nigeria
•Poland
•Russia
•Serbia and Montenegro
•Slovakia
•Slovenia
•South Korea
•Spain
•Sweden
•Switzerland
•Thailand
•Turkey
•Ukraine
•United Kingdom
•Vietnam
• Wildlife biologist monitor diseases of wild birds at the population level
• Sick or Dead Wildlife website reporting
• Bird Banding
• Hunter Surveillance
Wild Bird SurveillanceWild Bird Surveillance
http://www.michigan.gov/dnr
H5N1 Influenza in Humans-H5N1 Influenza in Humans-RiskRisk
Transmission from birds to humans does Transmission from birds to humans does not occur easilynot occur easily– Contact with feces or secretions from infected Contact with feces or secretions from infected
birdsbirds– Risk with butchering, preparing, defeathering Risk with butchering, preparing, defeathering
of infected birdsof infected birds– NOT transmitted through cooked foodNOT transmitted through cooked food
Implications for Human HealthImplications for Human Health
Asian Strain H5N1 in humans more aggressive Asian Strain H5N1 in humans more aggressive than seasonal flu strainsthan seasonal flu strains– Severe clinical courseSevere clinical course– Rapid deteriorationRapid deterioration– High fatalityHigh fatality– Low transmissibility human-to-humanLow transmissibility human-to-human
Incubation may be longer than seasonal influenzaIncubation may be longer than seasonal influenza– Seasonal influenza: 2-3 daysSeasonal influenza: 2-3 days– H5N1: possibly up to 10 daysH5N1: possibly up to 10 days
More studies neededMore studies needed
Confirmed Human Cases of H5N1Confirmed Human Cases of H5N1(WHO, 8/23/06)(WHO, 8/23/06)
CountryCountry H5N1 CasesH5N1 Cases FatalitiesFatalities Mortality Rate (%)Mortality Rate (%)
Azerbaijan 88 55 6363
CambodiaCambodia 66 66 100100
ChinaChina 2121 1414 6767
DjiboutiDjibouti 11 00 00
EgyptEgypt 1414 66 4343
IndonesiaIndonesia 6060 4646 7777
IraqIraq 22 22 100100
ThailandThailand 2424 1616 6767
TurkeyTurkey 1212 44 3333
VietnamVietnam 9393 4242 4545
TotalTotal 241241 141141 5959
What is the H5N1 Pandemic What is the H5N1 Pandemic Risk?Risk?
Three conditions must be met for a pandemic Three conditions must be met for a pandemic to start:to start:– Emergence of a new influenza subtypeEmergence of a new influenza subtype
– The strain infects humans causing The strain infects humans causing serious illnessserious illness
– Spreads easily between humansSpreads easily between humans
Each new H5N1 human case gives the virus Each new H5N1 human case gives the virus a chance to mutate into a highly a chance to mutate into a highly transmissible form, increasing the risk of a transmissible form, increasing the risk of a pandemicpandemic
MDCH Pandemic Influenza Plan MDCH Pandemic Influenza Plan 20052005
Revision of 2002 planRevision of 2002 plan
Released November 2005Released November 2005
Appendix to MDCH All-Hazards Response Appendix to MDCH All-Hazards Response PlanPlan
Pandemic plan updated as neededPandemic plan updated as needed
www.michigan.gov/influenzawww.michigan.gov/influenza
Leads for Public HealthLeads for Public Health
InternationalInternational: World Health Organization: World Health Organization
United StatesUnited States: Centers for Disease Control : Centers for Disease Control and Prevention, DHHSand Prevention, DHHS
MichiganMichigan: Michigan Department of : Michigan Department of Community HealthCommunity Health
CountyCounty: Local Health Department/Jurisdiction: Local Health Department/Jurisdiction
2020thth Century Influenza Century Influenza PandemicsPandemics
1918 – 1919, “Spanish Flu” (H1N1)1918 – 1919, “Spanish Flu” (H1N1)– Influenza A H1N1 viruses still circulate todayInfluenza A H1N1 viruses still circulate today– US mortality: approx. 500,000+ US mortality: approx. 500,000+
1957-58, “Asian Flu” (H2N2)1957-58, “Asian Flu” (H2N2)– Identified in China (February 1957) with spread to Identified in China (February 1957) with spread to
US by JuneUS by June– US mortality: 69,800US mortality: 69,800
1968-69, “Hong Kong Flu” (H3N2)1968-69, “Hong Kong Flu” (H3N2)– Influenza A H3N2 viruses still circulate todayInfluenza A H3N2 viruses still circulate today– First detected in Hong Kong (early 1968) and First detected in Hong Kong (early 1968) and
spread to US later that yearspread to US later that year– US mortality: 33,800US mortality: 33,800
Estimated Impact Estimated Impact of a Future Pandemic in of a Future Pandemic in
MichiganMichigan
(*Michigan figures developed with Flu-Aid 2.0 (*Michigan figures developed with Flu-Aid 2.0 software, CDC)software, CDC)
CharacteristicModerate
(1957 / ‘68-like)Severe
(1918-like)
Illness 3.4 million 3.4 million
Outpatient 2.5 million 1.5 million
Hospitalization 51,000 420,000
Deaths 15,000 125,000
Influenza SurveillanceInfluenza Surveillance
Michigan Disease Michigan Disease Surveillance SystemSurveillance SystemSentinel SurveillanceSentinel SurveillanceSyndromicSyndromic– PharmacyPharmacy– ERER
Laboratory Laboratory National National InternationalInternational
LHD’s/LHD’s/MDSSMDSS
Non-MDCH Non-MDCH LabsLabs
WHO DataWHO Data
CDC DataCDC DataLHD’s/LHD’s/
Healthcare Healthcare providersproviders
PharmacyPharmacy OTCOTC
Sentinel Sentinel PhysiciansPhysicians
ER ER SyndromicSyndromic
HospitalsHospitals
MDCH MDCH LabsLabs
Mi-FluMi-FluFocusFocus
Treatment OptionsTreatment Options
Antiviral MedicationsAntiviral Medications– Neuraminidase InhibitorsNeuraminidase Inhibitors
OseltamivirOseltamivir
ZanamivirZanamivir
Pandemic strain vaccinePandemic strain vaccine– Minimum 5 month production timeMinimum 5 month production time– Need chicken eggs and viral seed stockNeed chicken eggs and viral seed stock
Source: CDC
Oseltamivir- Not a PanaceaOseltamivir- Not a Panacea
Limited availability (one manufacturer)Limited availability (one manufacturer)
Personal stockpiling could lead to: Personal stockpiling could lead to:
– Inappropriate useInappropriate use
– Increased resistance by the virus Increased resistance by the virus (already one documented case)(already one documented case)
– Decreased availability for the critically illDecreased availability for the critically ill
For prophylaxis, multiple courses may be For prophylaxis, multiple courses may be needed throughout flu seasonneeded throughout flu season
Human Vaccine for Avian H5N1 Human Vaccine for Avian H5N1
Effective vaccine is not yet availableEffective vaccine is not yet available– Small batches of vaccine are undergoing Small batches of vaccine are undergoing
clinical trialsclinical trials– Not ready for mass productionNot ready for mass productionUS has advance-ordered 20,000,000 dosesUS has advance-ordered 20,000,000 dosesMay not match strain that causes pandemicMay not match strain that causes pandemicSeasonal influenza vaccine does not protect Seasonal influenza vaccine does not protect against H5N1 strainagainst H5N1 strain
Public Health:Non-Public Health:Non-Pharmaceutical InterventionsPharmaceutical Interventions
Social distancingSocial distancing– SchoolsSchools– Business practicesBusiness practices– Public gatheringsPublic gatherings
Respiratory/Cough Respiratory/Cough EtiquetteEtiquette
Hand HygieneHand Hygiene
Influenza Control MeasuresInfluenza Control MeasuresEducation to encourage prompt self-Education to encourage prompt self-diagnosisdiagnosisHand hygieneHand hygieneConsider masks, if possible, for Consider masks, if possible, for symptomatic persons (then send them symptomatic persons (then send them home!)home!)
Cancellation of school/social gatherings Cancellation of school/social gatherings QuarantinesQuarantines
Have a Plan!Have a Plan!
DevelopDevelop
ExerciseExercise
UpdateUpdate
ReviewReview
ExerciseExercise
Update….Update….
CDC/EOC-PHIL
Current U.S. StatusCurrent U.S. Status
No current evidence in U.S. of highly No current evidence in U.S. of highly pathogenic H5N1 inpathogenic H5N1 in
– Wild birdsWild birds– Domestic poultryDomestic poultry– HumansHumans
Images from: http://www.usda.gov/oc/photo
ConclusionConclusion
Many unknownsMany unknowns
Simple precautions go a long waySimple precautions go a long way
Education is critical to your COOPEducation is critical to your COOP
Get employees involved in the processGet employees involved in the process
Health AdviceHealth AdviceGood Now, Good in a PandemicGood Now, Good in a Pandemic
Get your annual flu shotGet your annual flu shot– Won’t protect against a pandemic strain Won’t protect against a pandemic strain
Stay at home if you have a feverStay at home if you have a fever
Wash hands with soap or hand Wash hands with soap or hand sanitizers when you sneeze or coughsanitizers when you sneeze or cough
Get adequate sleep, eat healthy, stay Get adequate sleep, eat healthy, stay hydratedhydrated
ReferencesReferences
pandemicflu.govpandemicflu.govMichigan Department of Community Michigan Department of Community Health (www.michigan.gov/flu)Health (www.michigan.gov/flu)www.who.intwww.who.intwww.cdc.govwww.cdc.govLocal Health DepartmentLocal Health DepartmentChamber of CommerceChamber of Commerce